﻿using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

 
using System.IO;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
 

namespace Dingding.Helper
{
   public class FileHelper
    {
        /// <summary>
        /// 将文件名解析成文件的上传路径
        /// </summary>
        /// <param name="fileName">文件名</param>
        /// <param name="path">文件路径</param>
        /// <returns path>文件在服务器上的路径</returns>
        public static String transPath(string fileName, string path)
        {
            createDir(path);
            //取服务器时间+8位随机码作为部分文件名，确保文件名无重复
            string nowStr = DateTime.Now.ToString("yyyyMMddhhmmssff") ;
            // 去掉后缀的文件名
            string fileNameStr = fileName.Substring(0, fileName.LastIndexOf("."));
            // 文件后缀
            String suffix = fileName.Substring(fileName.LastIndexOf(".") + 1);
            if (fileName.Trim() != "")
            {
                // 如果名称不为"",说明该文件存在，否则说明该文件不存在
                path += "\\" + fileNameStr + nowStr + "." + suffix;// 定义上传路径
            }
            return path;
        }
        /// <summary>
        /// 创建文件目录
        /// </summary>
        /// <param name="root">根目录</param>
        /// <returns ></returns>
        private static void createDir(String root)
        {
            // 检查目录
            if (!Directory.Exists(System.Web.HttpContext.Current.Server.MapPath(root)))
            {
                Directory.CreateDirectory(System.Web.HttpContext.Current.Server.MapPath(root));
            }
        }

        /// <summary>
        /// 根据文件在服务器上的路径下载文件，此处采用的是WebAPI的方式进行文件下载，下载成功后可自定义文件的保存路径
        /// </summary>
        /// <param name="fileName">文件名</param>
        /// <param name="path">文件路径</param>
        /// <returns></returns>
        public static HttpResponseMessage download(string fileName, string path)
        {
            try
            {
                var stream = new FileStream(path, FileMode.Open);
                HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
                response.Content = new StreamContent(stream);
                response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
                response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
                {
                    FileName = fileName
                };
                return response;
            }
            catch
            {
                return new HttpResponseMessage(HttpStatusCode.NoContent);
            }
        }
    
}}